Clínica Rementería | http://www.cirugiaocular.com COMPARATIVE STUDY OF CORNEAL THICKNESS MEASURES BY ULTRASOUND PACHYMETRY, CORNEAL TOPOGRAPHY AND ANTERIOR SEGMENT OPTICAL COHERENCE TOMOGRAPHY Trabajo presentado en la pasada edición del OPTOM Meeting Malaga 2013 por Sara Fernandez Cuenca.

1. N Minimum Maximum Average Deviation
OCT 10 526 570 545,10 13,568
Oculyzer 10 538 582 553,10 14,587
Ultrasonic
pachymeter
14 527 588 552,93 16,877
We included in the study 10 female patients with a mean age of 38 years, who met the following requirements:
- Do not have corneal pathology - Not to be carriers of previous contact lenses - Not having undergone refractive surgery
-
All examinations of the same patient were performed consecutively, trying to ensure no significant variation by hourly and hormonal changes , described in some
previous clinical studies.
The order in which the steps were performed was:
• Corneal topographer is the fastest equipment and it obtains more information: it gives the value of corneal thickness on all surfaces.
• Ultrasonic pachymetry may be affected by the instillation of anesthetic that has proven to cause a slight increase in the thickness that varies according to each person.
• Ultrasonic pachymeter is easier to carry.
• Both the topographer and OCT are more expensive that ultrasonic pachymetry.
• Corneal thickness measurement is reliable and accurate with any of these three equipments and there is a good or very good correlation between all the measurements
Table 1. Value of corneal pachymetry devices obtained in the three study.
ICC for individual
measures
ICC for measures
average
OCT y Oculyzer 0.982 0.991
OCT y Ultrasonic
pachymeter
0.750 0.857
Oculyzer y Ultrasonic
pachymeter
0.807 0.893
ICC value Strength of correlation
Higher to 0,90 Very good
0,71 to 0,90 Good
0,51 to 0,70 Moderate
0,31 to 0,50 Average
Minor to 0,30 Poor or absent
Table 2. Values ​​of intraclass correlation coefficients between measures of different devices. Table 3. Rating according to the values ​​matching the intraclass correlation coefficient (ICC).
CirrusHD-OCT (Carl ZeissMeditec) is based on the
principle of interferometry IR
Oculyzer (Alcon Labs), measurements obtained
by rotating Scheimpflug cameras
Ultrasonic pachymeter (Pocket II de
Quantel Medical), the only one invasive
2º 3º1º
• Lattimore MR, Jr. Kaupp, S. Schallhorn, S. Lew R. Orbscanpachymetry:implications of a repeated measures and diurnal variation analysis. Ophtalmology 1990;106:977-981
• Siu A, Herse D. The effect of age on human corneal thickness, statiscal implications of power analysis. ActaOphtalmol 1993;71:51-6
• Liu Z, Pugheider SC. Corneal thickness is reduced in dry eye. Cornea 1999;18:403-407
Pachymetry is the procedure whereby we measure the corneal thickness, ie, the distance between the front surface of epithelium and the posterior surface of corneal
endothelium. The importance of determining its value is that it is essential to detect corneal pathologies such as its thinning (ej. keratoconus) or thickening (ej. edema
with associated pathologies.) . It also helps to establish the true value of intraocular pressure (IOP) and to indicate or contraindicate corneal refractive surgery.
A few years ago, corneal thickness determination was performed by ultrasonic pachymetry but the rise of refractive surgery allowed the design of versatile equipment
which evaluate simultaneously several parameters. One of these equipments is optical coherence tomography (OCT) that, in addition to assess papilla and macula
thickness, it also meassures anterior pole and helps to determine corneal thickness in an specific and unique point of corneal topography maps . In this point, we can
obtain different parameters such as corneal curvature, refractive keratometry... and even thickness.
There are multiple studies analyzing the differences in corneal thickness between different human races, evolution with time, emotional states... but little about the
differences between equipments used in this study.
To evaluate accuracy, predictability and reliability of the equipments most commonly used in clinical practice for determining corneal thickness.
Figures 1, 2, 3 show the correlation between instruments pairs.
CONCLUSIONS
BIBLIOGRAPHY:
RESULTS:
PATIENTS, MATERIAL AND METHOD:
OBJECTIVES:
INTRODUCTION:
COMPARATIVE STUDY OF CORNEAL THICKNESS MEASURES BY
ULTRASOUND PACHYMETRY, CORNEAL TOPOGRAPHY AND ANTERIOR
SEGMENT OPTICAL COHERENCE TOMOGRAPHY
Fernández Cuenca S.1, Blázquez Sanchez V. 1
Dr. L. Álvarez-Rementería1, Dr. F.J. Hurtado Ceña 1
Clínica Rementería. Madrid. Spain.